Engine governor



May 26, 1959 R. H. THORNER ENGINE GOVERNOR 2 Sheets-Sheet 1 Filed Aug.13, 1958 v INVENTOR. 0 19055276. 7908/? R. H. THORNER ENGINE GOVERNORMay 26, 1959 2 Sheets-Sheet 2 Filed Aug. l3, 1958 M M m z mum s42\iaukmt ko owmui 5x5 Q 055$ o la :0 30 do 60 THROTTLE OPEN/N6 -D6PEE$ENG/NE RPM 4 TTORNEY United States Patent ENGINE GOVERNOR Robert HThomer, Detroit, Mich.

Application August 13, 1958, Serial No. 754,736

27 Claims. (Cl. 123-103) The present invention relates to speedgovernors for engines, and more particularly to governors operated byfluid pressure for use with internal combustion engines.

The present application is a continuation-in-part of my applicationSerial No. 291,381, filed June 3, 1952, entitled Fluid 'Operated SpeedGovernor, and of Serial No. 567,270, filed February 23, 1956, entitledEngine Governor.

One object of the present invention is to provide a governor for aninternal combustion engine which is simple and of low cost since anengine speed-driven element is not required, and which provides betterperformance and reliability than conventional velocity or vacuumgovernors.

Another object of the present invention is to provide a governor asdescribed in the preceding paragraph which includes a fluidservo-mechanism controlled by a frictionless pilot valve operated by anovel frictionless pressure responsive member sensing the pressures inthe intake passage of an internal combustion engine.

Another object of the present invention is to provide in a controlmechanism such as a speed governor, or in any fluid mechanism, a novelfrictionless pressure sensitive member, which has particular utility inthose applications where small size is desired.

A further object of the present invention is to provide a controlmechanism, or any fluid mechanism, as described in the precedingparagraph, having frictionless valve means operatively connected to thefrictionless pressure sensitive member for operation thereby ortherewith.

. These and other objects which will appear more clearly as thespecification proceeds, are accomplished, according to the presentinvention, by the arrangement and combination of elements set forth inthe following detailed description, defined in the appended claims andillustratively exemplified in the accompanying drawings, in which Fig. lis a partially schematic view, largely in cross section, showing oneform of the present governor operatively related to a carburetor andengine manifold or intake, and which uses the manifold vacuum as thecontrolling force;

Fig. 2 is an end elevation of a pilot valve housing section of the maingovernor case or housing, taken on the line 2--2 of Fig. 1;

Fig. 3 is a view partly in section, as along the line 3-3 in Fig. 1,showing an additional element of the pilot valve housing;

Fig. 4 is a chart showing typical variations of manifold vacuum withengine speed at various fixed throttle positions;

Fig. 5 is a chart showing the same data as in Fig. 4, plotted toillustrate the variation in manifold vacuum at various constant enginespeeds as the throttle opening is varied;

Fig. 6 is a perspective view showing relatively separated partsincluding a portion of one of a pair of flexible members forming aswingable support for the pilot valve assembly hereof;

Fig. 7 is a chart showing the characteristic performance of conventionalgovernors and the improved performance of the present invention; and

Fig. 8 is a schematic view similar to Fig. 1, showing a modified form ofthe present governor.

The term vacuum as used herein is to be interpreted as the differencebetween two absolute pressures; one pressure corresponding to theexisting atmosphere and the other pressure being sub-atmospheric, andaccordingly refers to the same physical state as though recited in termsof (absolute) pressure.

All vacuum and velocity governors now in commercial use utilize themanifold vacuum in the intake passage of an internal combustion engine.If engine vacuum is utilized as the engine speed signal, the problemsinvolved become extremely complex for reasons demonstrated below. Vacuumsensing governors differ in one important respect from governors thatutilize centrifugal flyweight means to produce the sensing forces. Forvacuum governors at each different position of the throttle a differentfunctional relationship of speed versus vacuum is available, whereas forcentrifugal-force-sensing governors the forces that vary with speed aresubstantially independent of variations in throttle position. Figs. 4and 5 show a family of curves of a typical internal combustion engineillustrating the characteristics of manifold vacuum which may be variedby means of two factors, and hence may be considered as being comprisedof two components as follows:

(1) The manifold vacuum may be varied by changing the engine speed atany fixed-throttle position; hence the manifold vacuum is responsive tochanges in engine speed, the vacuum increasing as the engine speedincreases. This component is herein referred to as speed vacuum.

(2) The manifold vacuum may be varied by changing the throttle positionat constant speed, hence the manifold vacuum is also responsive tochanges in throttle position, the vacuum increasing as the throttleopening decreases. This component is herein referred to as throttlevacuum.

Fig. 4 shows a typical family of curves illustrating variations invalues of the speed-vacuum which accompany changes of engine speed atvarious fixed positions of the throttle. The speed sensing forces whichmust be used by any vacuum governor are functions of the minute changesin pressure which result from small changes in speed along each of theillustrated curves. As indicated by the decreasing slope of the variouscurves at the higher engine speeds, the pressure change per unit ofspeed becomes progressively less, thus making it increasingly difficultfor the speed-sensing-mechanism of any vacuum governor to besufficiently sensitive at high engine speeds.

Fig. 5 shows typical curves (which may be plotted from data taken fromFig. 4) illustrating the variations of manifold vacuum as thethrottle-opening is varied at diiferent constant engine speeds, whichcurves represent the throttle vacuum as above defined. In order toproduce satisfactory speed regulation, suitable mechanism or means mustbe provided in a vacuum governor to compensate for the efiects ofthrottle-vacuum variation. The method of obtaining such satisfactoryspeed regulation with the present governor, in its illustrated forms, isin effect to extract from the intake manifold vacuum the pressures whichvary as a function of engine speed (speed-vacuum) for use as aspeed-sensing force, and to compensate for the inherent variations inmanifold vacuum which accompany changes in throttle position (throttlevacuum).

3 Governor construction Referring to Fig. l, a governor housing 1 ispositioned between and sealed to a downdraft carburetor 2 and the engineintake manifold partially shown at 3. The form of the governorillustrated in Fig. 1 is of the sandwich type as opposed to the type ofgovernor forming a built-in portion of the carburetor assembly, althougheither form may be used for the governor of the present invention. Inthe form shown, the governor controls the engine speed through operationof a governor throttle 4 which is separate from a carburetor throttle 5.In the built-in type of governor, the governor throttle and carburetorthrottle are one and the same. The throttle 4 is locatedon thedownstream side of the carburetor venturi 6 and the throttle 5 which isconnected for operation by the driver through suitable and conventionalaccelerator linkage (not shown). Fuel is admitted to the air at thecarburetor venturi throat 6 before the air reaches the throttle 5. Inthe arrangement shown, the engine speed is controlled by automaticoperation of the governor throttle 4 only when the carburetor throttle 5is opened sufficiently to allow the engine to exceed the governed speed.The throttle 4 is mounted on a suitable shaft 4a journalled in thehousing 1 and actuated by a pressure responsive member such as adiaphragm 9 through a link 11 which operably connects the diaphragm withthe throttle 4.

The present governor, as illustrated in Fig. 1, includes a poweramplifier having a fluid bleed air flow circuit to provide a'source ofenergy controlled by a pilot valve mechanism, generally indicated at 20arranged to modulate pressures acting on the power member (diaphragm 9or its equivalent such as a piston or bellows) of the amplifier. In theillustrated type of pressure modulation system at least two restrictionsor orifices are provided in series in the fluid circuit, and the pilotvalve is actuated by speed responsive means to vary the aperture of atleast one of the orifices. In order to obtain a large range of pressurecontrol for a given amount of pilot valve movement, the pilot valve inthe form shown operates simultaneously to vary the apertures of both ofthe orifices. Although in the form of the invention illustrated in Fig.1 air is used as the working fluid, any pressure fluid such as oil forexample, may be used. The present governor according to Fig. 1 has asingle-acting servo-motor with a position type modulating pilot valveaction, whereas the governor according to Fig. 8 hereof (to bediscussed) has a double-acting servo-motor with an excursion typemodulating pilot valve action. The fluid servo-motor controlled by apilot valve, as shown herein, is equivalent to other servo-motors suchas a solenoid or electric motor controlled by switching means in anelectric circuit.

The fluid servo-motor, in the form illustrated in Fig. 1, comprises adiaphragm 9 secured to housing 1 by a suitable cover to provide achamber 13 on one side of the diaphragm and a chamber 15 on its otherside. The chambers 15a and 15b defined by the housing walls are in openend unrestricted communication with chamber 15. In the abovementionedcircuit as shown by arrows, air from the carburetor entrance 17 flowsthrough a conduit or passage 21, through an inlet orifice 23, through achamber 25 which communicates with chamber 13 by means of a passage 27,through an outlet orifice 29, through a chamber 31 and out throughpassage 33 to the intake manifold at 35. The passage 33 is sufiicientlylarge that the pressure in chamber 31 is substantially the same as thepressure in the intake passage at 35 on the downstream side of thethrottle. Thus, since negligible line/loss is produced by the passage33, the chamber 31 in the form shown is subjected to the full vacuum inthe manifold at 35. This large passage is also desirable for operationof the novel speed sensing member to be described. Furthermore variousother portions of the circuit including conduit 21 are large enough tominimize line-loss so that the pressure transmitted through chamber 15ato the inlet orifice 23 is substantially undiminished from that in thecarburetor entrance 17.

The pressures in the above-described circuit (in chamber 25) transmittedto the diaphragm 9 for positioning thereof are controlled by a movablepilot valve element 37, hereinafter referred to as pilot-valve. In itspreferred form, the pilot valve has oppositely tapered valve faces 39and 41 which are maintained in proper cooperative relationship to theorifices 23 and 29, respectively, by means to be described. The pressurein the chamber 25 is statically transmitted and hence is substantiallyequal to the pressure in chamber 13 at all times. In some installationsit may be necessary or desirable to damp the movements of diaphragm 9.In such cases a suitable damping means may be provided by a restriction27a in passage 27.

The movements of the pilot valve 37 in response to speed-changes causethe valve faces 39 and 41 gradually to reduce the eifective aperture ofone of the two orifices 23 and 29 and simultaneously to increase theeffective aperture of the other orifice. In this manner the illustratedpilot valve 37 modulates the pressure in the chambers 25 and 13 to anyvalue from the pressure at the entrance of orifice 23 (same as atcarburetor entrance 17) when the valve face 41 seats in orifice 29 tothe value of pressure at the outlet of orifice 29 (unmodified manifoldvacuum) when the valve face 39 seats in orifice 23. Thus the pilot valvein its travel between these two extreme positions can cause any pressureto be applied to diaphragm 9 between the above-mentioned extreme valuesof pressure. The fluid-bleed-circuit as above described is provided forthe purpose of pressure control. The actual quantitative amount of airwhich flows through the circuit is not important in itself but isincidental to the pressure-conrolling function thereof. The flow of airmay be minimized by properly sizing the pilot valve and its cooperatingorifices to prevent lean idle mixtures and excessive idle speeds of thecontrolled engine, although the orifices must be large enough to permitsufiicient speed of response of diaphragm 9.

The diaphragm 9 is biased in a direction to oppose the pressure (vacuum)in chamber 13 by a suitable spring 43 which, for example, may be securedat one end to the housing (in chamber 15a) and having its other endconnected to the throttle 4 in a manner to urge the throttle toward itswide-open-position at which it is suitably stopped.

With the foregoing construction as described, any travel-position of thepilot valve 37 will produce corresponding but amplified travel-positionsof the diaphragm 9 and throttle 4, and the positioning of the diaphragm9 is accomplished by changes in force exerted by the spring 43 inrelation to the vacuum in chamber 13.

The pilot valve 37, as shown, is supported for frictionless movements byleaf spring members 45 and 47 each of which is secured at one endthereof to the pilot valve 37 and at the other end to the valve housing49 as shown in detail in Fig. 6. As shown in Fig. 6, each leaf springhas an elongated hole 153 or the equivalent to permit universal movementof the valve faces 39 and 41 when they are alternately held againsttheir seats 23 and 29, respectively, and the retaining screws 152 aretightened. The screws are inserted through their respective leaf springsinto threads 154, and anti-torque members such as member 155, which maybe pre-bent as shown to provide a lock-washer action, are insertedbetween the screw heads 152 and their respective leaf springs 45 or 47.When the valve faces are alternately held against their seats tocompensate for all eccentricity (regardless of production variations)and the correspondthen contacts the surface 150 in rotary abutment. Withthis construction only thrust is transmitted to the leaf springs so theyare maintained in their set position While the screw is being tightened.

When the pilot valve travels between its two extreme positions, it issubject only to air contact and is entirely free from the usualdetrimental effects of static and kinetic friction. The present pilotvalve is also entirely free from the adverse effects usually encounteredin sliding type pilot valves as a result of dirt and gum wedging betweenthe close-fitting surfaces thereof. Thus the present pilot valve and itsassociated mechanism is capable of immediate response to extremely smallforces applied axially of the valve.

In the specification and claims herein, as well as in other patents ofthe applicant, the supporting leaf springs have been referred to assubstantially frictionless. The leaf-spring-supports for the pilot valveactually are completely frictionless from a practical standpoint sincein extensive tests of the pilot-valve-action by itself when supported byleaf springs, no lag or hysteresis could be measured. Any intermolecularfriction in the material itself can, of course, be disregarded since itis immeasurably small. But the term substantially has been used solelyto recognize this minute intermolecular friction.

The pilot valve is actuated in response to changes in pressure in theintake manifold at 35 (through passages 31 and 33) by a frictionlessspeed-sensing means which in the form shown, comprises a circular (orother suitably shaped) disc 51 of small diameter secured to the pilotvalve 37 and movable in relation to a cylinder 50 which may be formed asa flange outstruck from a disc-housing plate '53. Thus, the disc isdisposed in the aperture of the cylinder to comprise a movable portionof a wall of chamber 31. The disc 51 is mounted by suitable means as bysoldering rigidly to a stem portion of the pilot valve 37, so that thedisc, in the form shown, is also supported by the leaf springs 45 and 47for frictionless movements in relation to its cylinder 50. Suchfrictionless movements are made possible by providing substantiallyuniform perimetrical clearance between the cylinder and the disc, whichclearance is maintained by the rigidity of the leaf springs in adirection substantially transverse to the direction of movement of thedisc. Incident to the provision of the perimetrical clearance, anegligible amount of air must continuously bleed through the smallclearance space (such as .004 in. diametrically) between the disc 51 andits cylinder 50 under the influence of manifold vacuum. As illustrated,the flow of air through the branch air bleed past the disc 51 is fromconduit 21, through passage 59, through chamber 151), through theclearance around the disc and into chamber 31, Where the branch airbleed or circuit joins the main portion of the fiuid bleed circuit, andthe combined air-flow passes to the intake passage through conduit 33,which is suificiently large to produce negligible loss therein, aspreviously discussed. By providing this large unrestricted passage, thefull vacuum in the intake manifold is applied to the disc despite thebleed of air through the perimetrical clearance space around the disc.Such bleed of air occurs since the disc is exposed on one side thereofto substantially undiminished intake passage vacuum in chamber 31 and onits opposite side to substantially undiminished carburetor entrancepressure at 17, 21, 59 and 15b.

In order to provide a practical arrangement of the disc as africtionless sensing member, suitable means are provided to permitsubstantially concentric adjustment of the clearance space around thedisc without the necessity of maintaining close tolerances of theconcentricity of the parts in production. In the form shown, a dischousing plate 53 is secured to the valve housing 49 by suitable means asby the screws 55, whereby the disc generally separates chamber 31 fromchamber 15b. The

plate 53 has holes 53a which are oversize in relation to the shanks 55aof the screws 55 as viewed partly in cross section in Fig. 3. With thisconstruction the plate is adapted to be moved in various directions inits principal plane before being secured in place by tightening thescrews 55. Such construction enables substantially concentric adjustmentof the cylinder 50 in relation to the disc 51 during assembly of thegovernor to provide a substantially uniform perimetrical clearancebetween the cylinder and the disc. A detachable cover 57 encloses theplate 53 and disc 51, and an opening 53b in the plate registers with apassage 59 in valve housing 49 to connect the chambers 15a and 15b forunrestricted flow of arr.

The freely swingable or free floating support for the pilot valveprovided by the leaf springs 45 and 47 and features thereof to bedescribed later maintains the peripheral surface of the disc 51 out ofcontact with its cooperating cylinder 5ft so that both the pilot valveand disc are completely free from restraining contact friction at alltimes.

Thus, the leaf spring supports provide not only for frictionlessmovement of the pilot valve, but in the forms shown, serve to supportwithout friction the entire speed sensing mechanism. The sensingmechanism may be defined herein as including all parts that must respondto the minute changes in vacuum that are produced by small changes inspeed and comprise the pilot valve 37, the leaf springs 45 and 47, thedisc 51, the retainer 63, and spring 61.

The novel pressure sensitive member (disc 51) having perimetricalclearance and supported by leaf springs for frictionless movements hasbeen illustrated in the environment of a vacuum sensing speed governor.While this frictionless speed sensing means has particular utility inthis vacuum governor combination, I recognize that it also has utilityin any kind of speed governor or in any other loop type automaticcontrol mechanisms such as disclosed in Fig. 3 of my said co-pendingapplication, Serial No. 291,381; or the frictionless pressure sensitivemember can also provide particular utility in any fluid mechanismrequiring a frictionless pressure sensitive member, particularly whensmall size is required. For example, the disc 51 in the vacuum governorabove-described has a diameter of about /2 inch, and has beensuccessfully operated with a diameter of only inch. By way ofcomparison, if a rubber or fabric diaphragm of this small size wereused, for small pressure changes the diaphragm would provide excessivelag or hysteresis. If a metallic bellows of this small size were used,it would have an excessive spring rate which becomes part of the springbiasing system (such as spring 61), and for all sizes of bellows thespring rate varies in production about 20 to 40%, which is excessive.However the disc 51, per se, does not have a spring rate since it floatsin fluid without contacting the perimetrical surface of the aperture ofthe cylinder 50.

If the leaf-spring supported disc is included in a mechanism notrequiring valve means, instead of the concentricity adjustment shown inFig. 3 and above-described the perimetrical clearance of the disc inrelation to the aperture 50 of the housing 53 may be adjusted by thestructure of Fig. 6. With this adjusting mechanism, the leaf spring 45or 47 is moved in any direction in its own plane until the perimetricaldisc clearance is substantially uniform; and then the screws 152 aretightened while the anti-torque members 155 prevent torque from beingtransmitted to the leaf spring.

The forces acting axially on the pilot valve produced by fluid pressureon the disc 51 are opposed by the force of a coil spring 61 mountedbetween the pilot valve and a throttle-vacuum compensating cam mechanismassembly 60 connected to move with the throttle 4. The spring 61, asshown, is supported at the valve-end by a spring retainer 63 secured tothe pilot valve 37 for sub assassin stantially frictionless movementstherewith and at the other end by an adjustable spring retainer 65. Thespring retainer 65 is supported for movement approximately along theaxis of the pilot valve by a swingable arm 67 having a fixed fulcrumprovided as shown by a hinge pin 69 secured to the housing. The oppositefree end of the arm 67 is pivotedly secured to a yoke member 71 having athreaded stem portion 71a extending into complementary threads of theadjustable retainer 65 (shown knurled to facilitate adjustment). Theswingable arm 67 and the yoke 71 and spring retainer 65 are securedtogether for free pivotal relative movement by a suitable connecting pin73.

The spring 61 is supported in position at all times during governoroperation by means of a slight preloading between its two retainers 63and 65, which preloading occurs incident to the normal calibration ofthe device. The spring retainers illustrated in Fig. l havefrusto-conical guide portions disposed to freely enter the spring endsfor the support thereof. The spring 61 is adjusted for setting governorspeed within a practical range (for a given contour of a cam 81 to bediscussed) by turning the spring retainer 65 about its threadedconnection with yoke 71.

The reset mechanism 60 is provided by the present invention tocompensate for throttle-vacuum and includes a novel adjustment forspeed-droop (speed-regulation). Referring to Fig. 1, the throttle shaft4a carries a cam mounting block or member 75 suitably secured to theshaft as by a screw or pressing. The link 11 of the diaphragm 9, asshown, is operatively connected to a plate 79 suitably rigid with themounting block 75 and throttle shaft 4a. A bent portion 11a of the link11 extends through an opening in the plate 79. A hook 79a of the plate79 is shown in Fig. 1 as comprising a support for one end of the spring43. A cam 81 which is shown in the form of a plate is apertured forsupport by the free end of the throttle shaft 4a for rotationaladjustment of the cam relative to the shaft. The cam 81 is secured tothe mounting block 75 by a screw 83 projecting through an arcuate slot85 of the cam into a threaded opening in block 75. Rotary adjustment ofthe cam through small increments is facilitated by a pin 87 rotatable ina socket or bore of the mounting block 75. Pin 87 has a relativelyeccentric portion 87a of reduced diameter projecting through a slot 88of the cam 81 shown as extending radially of the throttle shaft axis.The eccentric portion 87a is provided with a. slot or its equivalent 87bfor engagement by a suitable adjusting tool. The angular position of thecam is adjusted by loosening the screw 83 and revolving the eccentricportion 87a which cooperates with the radial slot 88 to revolve the camas required to give the desired speed-droop. The screw 83 is thentightened to lock the cam in the adjusted position. A more completedisclosure of this reset mechanism 60 is provided in my co-pendingapplication, Serial No. 567,270.

The cam contour is represented in Fig. 1 by the curved surface contourportion 81a of the cam 81 and is disposed for operative contact with theswingable arm 67 either directly with the arm or through a suitablecamfollower wheel or roller 67a mounted on the arm 67, as on a pin 73.The contour portion 81a is developed to vary the biasing force of thespring 61 acting on the pilot valve in accordance with the variouspositions of the throttle 4. Assuming proper calibration of the camcontour 81a, the biasing force of the spring 61 which opposes the forcesproduced by vacuum acting on the disc 51 increases and decreases as afunction of the increase and decrease of throttle vacuum whichaccompanies throttle closing and opening movements, respectively.

The left end of the spring 61 as viewed in Fig. 1 is in effect supportedsolely by the pilot valve 37 which, to gether with the disc 51 (alsomounted on the pilot valve), is guided for free-floating movement by thesupporting 8 leaf springs 65 and 47. Thus, none of thespeed-sensingelements of the governor are subjected to restraint bystatic or kinetic friction. The speed sensing elements of the governorspeed-sensing mechanism as previously defined exclude the adjustablespring retainer 65 since it does not move in response to speed changesas will be shown.

Operation The governor mechanism as above described operates as follows:Assume that an automotive engine is under stable operation controlled bythe governor wherein the throttle 4!- would be in substantially a fixedposition. If the engine load decreases as when the vehicle descends ahill, such change in load and resulting increase in engine speedproduces a speed change signal in the form of an increase in vacuum inthe intake manifold at 35 and chamber 31 acting on the disc 51 to effectmovement of the pilot valve 37 to the right, as viewed in Fig. 1. Suchspeed-effected movement of the pilot valve 37 produces an increase inthe vacuum transmitted to chamber 13 which initiates movement of thethrottle 4 towards its closed position and tends to restore the governedspeed.

Such movement of the throttle 4 toward closed position as a result ofincreased engine speed from the initial assumed fixed-throttle positionproduces an increase in throttle-vacuum as illustrated in Fig. 5.Without compensation, the increased throttle vacuum acting on the disc51 would produce further movement of the disc and pilot valverightwardly which would transmit more vacuum to the diaphragm 9 which,in turn, would apply still more throttle vacuum to the disc until thethrottle 4 completely closes.

Such detrimental effects of the throttle vacuum are compensated for bythe cam mechanism 60 above de' scribed. As the throttle 4 is rotated ina closing direction (clockwise), the cam 81 is revolved therewith; thismovement of the cam acts to increase the effective force of the spring61 acting on the disc 51 (transmitted through the pilot valve 37)sufficiently to compensate for or balance the increased force producedon the disc 51 by the increased vacuum which accompanies movements ofthe throttle in restoring the governed speed. The contour 81a of the cam81 can be profiled in effect to balance at all positions of the throttlesuch forces produced by throttlevacuum" acting on the disc, wherebymovements of the disc are substantially responsive to changes inmanifold vacuum that accompany changes in engine speed (speed vacuum).

It is apparent from the foregoing that during any stable condition, theinitial change of speed detected by the governor speed-sensing-mechanism(51, 37, 61, etc.) incident to a change in load occurs at substantiallya fixedthrottle-position; and as the throttle is moved to maintain thedesired governed speed at the new load, the cam operates in effect torender the disc 51 substantially insensitive to the pressure changesacting on the disc which accompany such changes in throttle position.When the engine load is increased, as when the vehicle ascends a hill,the actions of the governor are exactly the reverse of those describedabove. A more complete discussion of the basic governor operation ispresented in my said application, Serial No. 567,270.

In actual operation entirely from a mechanical or physical standpoint,the arm 67, retainer assembly 71, 65 and spring 61 might be consideredas a connecting link or a shaft. Considered only from this mechanical orphysical aspect, it might be said that the cam 81 acts to position thepilot valve 37 by means of a connecting shaft whose length varies withspeed-vacuum and throttle-vacuum. Considered in this manner, thevalve-end of the spring would be subjected to speed-sensing movements,whereas the cam-end of the spring would be subjected to movements tocompensate for throttle vacuum or load changes.

asszaoo In the operation of the present governor as shown in Fig. 1, ifthe cam 81 were calibrated to compensate completely for thethrottle-vacuum at the governed speed, the travel of the pilot valve 37would be responsive substantially solely to engine speed. Under theseconditions, the pilot valve would assume a new position with each smallchange in speed because the changing force of v the spring 43 whichopposes movement of the diaphragm 9 necessitates a correspondinglychanging vacuum in chamber 13 to move the throttle 4 throughout itstravel. Under these conditions, this changing vacuum in chamber 13 canonly be produced by a gradual displacement of the pilot-valve which mustbe produced by small changes of engine speed (speed-droop) as the engineload varies from full-load to no-load.

Furthermore the present governor in the form shown has a servo-motor(diaphragm 9) biased by a spring 43 in which only one chamber of theservo-motor is controlled by pilot valve 37 which modulates thepressures acting on the servo-motor. With such a construction in theabove assumed condition (which would be equivalent to having the pilotvalve operated by a force varying substantially solely as a function ofspeed independent of the throttle position), a slightly different enginespeed is required during governor operation for each position of thethrottle as the load is varied from no-load to fullload, whereby thegovernor inherently would produce a speed droop. Hence this form of thepresent governor provides a position type pilot valve action rather thanan excursion type pilot-valve-action, which will be discussed inreference to Fig. 8. As explained above, the governor would theninherently produce a speed-droop as shown by the curve DW, Fig. 7, againassuming that the cam is calibrated to compensate entirely forthrottlevacuum at the governed speed.

The angular adjustment of the cam 81 in relation to the throttle shaft4a is provided for several reasons. Firstly, it can be seen in Fig. 5that the variation in vacuum with throttle positon increases at a veryhigh rate with small change in throttle movement toward closed position,particularly between and 20 degrees. Since the contour of each camreflects the shape of one of the curves shown in Fig. 5, the angularrelationship between the cam and the throttle 4 is important. If, inproduction, the cam were secured to the throttle in fixed angularrelationship, any slight production variations could produceinconsistent operation of one governor in relation to another having thesame design and intended cam calibration. Such production variationshave no detrimental effects in the present governor since the angularposition of the cam may be set as required in each governor unit.

Secondly, and very important, the angular positioning means for the camserves to provide an excellent speeddroop adjustment. Before consideringthe problem of speed-droop control, refer to Fig. 7 which shows a curveof horsepower versus engine speed at wide-open-throttle. The curve ECrepresents regulation of a typical velocity governor as compared toisochronous operation such as illustrated by the curve DC. With avelocity governor, as the engine is loaded from no-load at C tofull-load at E a speed-droop is produced corresponding to O-V which canbe as much as 500 r.p.m. or more, for example, and a power loss occurssuch as represented by distance P in Fig. 7. The cam of the presentgovernor can be profiled to produce a loading curve having a speed droopas illustrated by the curve BW. With such a calibration, if the cam 81is revolved slightly in rela tion to the throttle shaft 4a in acounterclockwise direction by the eccentric 87a, the isochronous curveD-C shown in Fig. 7 may be approached or attained. However, in anothermethod of controlling speed-droop the governor may be calibrated toprovide substantially zero speed droop or isochronous operation bycontouring the cam as required whereby adjustment of the cam 81. in aclockwise direction will cause the governor to operate with any desiredspeed droop. Such angular movement of the cam would, in effect, causethe isochronous loading curve D-C to swing as though hinged at D wherebypoint C is moved rightwardly to give a curve similar to DW.

As described previously, the speed of the engine controlled by thegovernor may be set by rotary adjustment of the spring retainer 65. Inview of the fact that the cam 81, as illustrated in Fig. 1, reflects thecontour of a single throttle-vacuum curve as shown in Fig. 5, and sincethe curves shown in Fig. 5 are not parallel, only a limited range ofgoverned speeds is obtainable by adjustment of the seat member 65 when asingle cam contour is used. Accordingly, in order to providesatisfactory regulation over a large range of engine speeds, as from1600 r.p.m. to 3800 r.p.m. for example, the governor can be furnishedwith a plurality of cams for selective use. As an alternative, the camcontours corresponding to various throttle vacuum curves (as in Fig. 5)can be provided on a single suitably adjustable three dimension cam asshown in my Patent No. 2,736,304.

In the operation of the governor as above described, the disc 51actually provides two distinct functions. In Fig. 1, the manifold vacuumin chamber 31 acts on the exposed area of the pilot valve, which area issubstantially equal to the aperture of orifice 29. Since this vacuumvaries widely as shown in Figs. 4 and 5, it tends to produce a varyingunbalancing force acting on the pilot valve itself, which unbalanceforce would tend to disturb the desired positioning and response of thepilot valve to changes in engine speed. However, the disc 51 is also ex:posed at all times to the same vacuum in chamber 31 that acts on thepilot valve. Hence an area of the disc equivalent to the exposed area ofthe pilot valve provides one of the above-mentioned functions in whichthe vacuum force produced by such equivalent area of the disc cancels orbalances the vacuum force acting on the pilot valve. In this manner thevalve is made substantially independent of the variations of vacuumacting thereon. Such equivalent area of the disc is illustrated in Fig.2 by the dotted circle which is the projection of orifice 29. Then theremaining annular area of the disc 51 provides the second function whichis to sense speed changes in the manifold vacuum as above described.

Fig. 8 illustrates basically the same system and construction as shownin Fig. 1, difiering therefrom principally in that the servo-motor isdouble-acting in response to fluid pressure difierential and withappropriate modifications of the pilot valve mechanism for such action.Thus the diaphragm 9a under control of the pilot valve mechanism issubjected to pressure (vacuum) for movement in both directions withoutthe use of spring return, whereby the vacuum in chamber 102 performs theequivalent function of the diaphragm return spring 43 of the form shownin Fig. 1. Chamber 104 is sealed at the link 11 by a flexiblebellows-type seal 106 of small area. The pilot valve assembly 108, asshown, is constructed similarly to the corresponding assembly 20 of Fig.1 except that twice the number of valve orifices and coacting movablevalve elements are provided to modulate oppositely the pressures in thetwo diaphragm chambers 102 and 104 through passages 110 and 112,respectively.

The air flow or control circuit of Fig. 8 in effect comprises twobranches, each similar to the circuits described in relation to Fig. 1,arranged in parallel. Each of the two parallel branch circuits includean inlet valve or variable restriction at orifices 114 and 116,respectively, exposed to the atmosphere and an outlet variablerestriction at orifices 118 and 120, respectively, opening into achamber 124 which communicates with the manifold vacuum through passage33 as shown. The pilot valve 122 includes the four illustrated taperedvalve faces for modulating-control of the apertures of orifices 116 andasst/399sllll 118 while oppositely and simultaneously controlling theapertures of the orifices 120 and 114.

In operation, as the pilot valve is moved to the left by the disc 51when the engine speed increases, the vacuum in chamber 104 is increasedand the vacuum in chamber 102 is simultaneously decreased by such valvemovement to effect movement of the throttle in a direction to reducespeed. Such throttle movement is accompanied by counterclockwisemovements of the cam 81 of mecha' nism 128 to provide the desiredcompensation for throttle-vacuum acting on the disc. When the enginespeed decreases, the valve movement and all operations initiated therebyin the governor are the reverse of those just above described.

The pilot valve of the form of the governor shown in Fig. 8 was referredto earlier herein as an excursion type valve mechanism as compared tothe position type valve mechanism of Fig. l in which the pilot-valve 37assumes different travel-positions as the load is varied throughout theload range during governor operation, assuming full compensation forthrottle vacuum. If the contour of the cam 81 of the governor shown inFig. 8 were calibrated to compensate exactly for the change inthrottle-vacuum at the governed speed, then the travel of the pilotvalve would be responsive substantially only to engine speed. Since inthe arrangement of Fig. 8 the diaphragm 9a is actuated solely by changesin pressure on opposite sides thereof, the diaphragm would continue tomove if the pilot valve is moved and maintained at a distance from itsmid-position. Hence in order to provide a stable governor, the pilotvalve must operate by intermittent excursions from substantially itsmid-position. The valve must return after each such excursion tosubstantially a neutral or mid-position in order to stabilize thegovernor. There is substantially one neutral position for the pilotvalve, and (again assuming complete throttle-vacuum compensation) thevalve can only remain in this one neutral position at only one enginespeed because the biasing force of the spring 126 varies slightly as thepilot valve moves. Since, as assumed, the stable condition of thegovernor corresponds to substantially a single position of the pilotvalve and hence only one force of the spring 126, isochronous or nearisochronous governor operation is produced.

I wish it understood that my invention is not limited to any specificconstruction, arrangement or form of the parts, as it is capable ofnumerous modifications and changes without departing from the spirit ofthe claims.

What I claim is:

1. In a governor for an internal combustion engine having an air intakepassage for the flow of air therethrough, a governor throttleoperatively mounted within said passage to control the speed of theengine, a pressure responsive member operatively connected to saidthrottle for actuation thereof, a circuit having a flow of fluidtherethrough and communicating with said pressure responsive member,valve means in said circuit to control pressure therein acting on saidpressure responsive member to effect speed controlling movements thereofin response to movements of said valve means, a pressure chamber havingan aperture and communicating with said air in said intake passage, apressure sensitive member exposed to said air in said chamber and actingon said valve means to effect speed-responsive movements thereof inresponse at fixed positions of said throttle to changes in intakepassage air pressure existing in said chamber, means operativelyassociated with said throttle and adapted to produce forces acting onsaid valve means and varying in accordance with positions of saidthrottle, said pressure sensitive member comprising a rigid memberdisposed within said aperture to comprise a movable portion of a Wall ofsaid chamber, means to mount said rigid member to provide apredetermined clearance space between its perimetrical surface and theadjacent surface forming said aperture, the air which acts on said rigidmember passing through said clearance space whenever a pressuredifferential exists on opposite sides of said rigid member, saidmounting means including substantially frictionless swingable meansimparting rigidity in one direction and acting to support said rigidmember and maintain said perimetrical clearance in all operativepositions of said rigid member for substantially frictionless movementsin a direction transverse to said first named direction, said swingablemeans also acting to support said valve means for substantiallyfrictionless movements in said direction transverse to said first nameddirection by maintaining said valve means suspended within the fluidcontrolled thereby completely free of surface contact other than aircontact during operational movements thereof, whereby saidspeed-controlling movements of said valve means and said pressuresensitive member are substantially instantaneous and consistent inresponding to said changes in intake passage pressure at fixed-throttlepositions.

2. In a fluid mechanism having a fluid chamber with an aperture therein,a fluid pressure sensitive member disposed within said aperture tocomprise a movable portion of a wall of said chamber, means to mountsaid pressure sensitive member and to position same to provide apredetermined clearance space between its perimetrical surface and theadjacent surface forming said aperture, the fluid which acts on saidpressure sensitive member passing through said clearance space whenevera pressure differential exists on opposite sides of said member, saidmounting means including substantially frictionless swingable meansimparting rigidity in one direction and acting to maintain saidperimetrical clearance in all operative positions of said member forsubstantially frictionless movements in a direction transverse to saidfirst named direction.

3. The combination of elements defined in claim 2, in which saidmechanism includes a fixed portion, and said swingable means includes atleast one leaf spring member, one end of said leaf spring member beingoperatively secured to said pressure sensitive member, threadedfastening means including a head means to secure the other end of saidleaf spring member to said fixed portion of said mechanism, said leafspring mem' ber including sufiicient clearance relative to saidfastening means to provide adjustment of said pressure sensitive memberin relation to said aperture in a direction substantially parallel tothe plane of said leaf spring member for making said clearancesubstantially uniform perimetrically of said pressure sensitive member,and an antitorque member between said head and said leaf spring membercooperating with said fixed portion to prevent the torque of said headfrom acting on said leaf spring member when said head is tightened fortransmitting only thrust forces to said leaf spring member to maintainsaid adjusted perimetrical clearance.

4. In a self-regulating control mechanism for automatically controllinga variable condition, the combination of control means to regulate saidcontrolled condition, a pressure responsive member operatively connectedto said controlled means for actuation thereof, a fluid circuit having asource of fluid pressure to produce a flow of fluid therethrough andcommunicating with said pressure responsive member, valve meansincluding a movable valve member in said circuit for controlling thefluid pressure therein acting on said pressure responsive member toeffect movements thereof and said control means, means associated withsaid valve means to apply forces thereon for afiecting the positioningthereof to effect regulating movements of said control means, a fluidchamber having an aperture therein, said last named force-applying meansincluding a pressure sensitive member disposed within said aperture tocomprise a movable portion of a wall of said chamber, means to mountsaid pressure sensitive member and to position same to provide apredetermined clearance space between its perimetrical surface and the13 adjacent surface forming said aperture, the fluid which acts on saidpressure sensitive member passing through said clearance space whenevera pressure differential exists on opposite sides of said member, saidmounting means including substantially frictionless swingable meansimparting rigidity in one direction and acting to maintain saidperimetrical clearance in all operative positions of said pressuresensitive member for substantially frictionless movements in a directiontransverse to said firstnamed direction, said source fluid pressureacting on an area of said valve member to produce undesirable forcestending to affect the desired positioning thereof, and said pressuresensitive member having an area subjected to said source fluid pressureto produce forces in a direction opposite to that of said undesirableforces to compensate therefor in any desired amount.

5. The combination of elements defined in claim 4, and said swingablemeans also acting to support said valve member for substantiallyfrictionless movements in said direction transverse to said first-nameddirection by maintaining said valve member suspended within the fluidcontrolled thereby completely free of surface contact other than fluidcontact during operational movements thereof, and in which said valvemember controls pressure on only one side of said pressure responsivemember, the configuration of said valve member being adapted to producemodulated pressures acting on said one side of said pressure responsivemember to effect movements thereof as a function of the position of saidvalve member, spring means acting on said pressure responsive member tooppose the forces thereof produced by said pressure acting on said oneside of said pressure responsive member, and second spring means actingon said valve member to establish the position thereof.

6. The combination of elements defined in claim 1, and said mechanismincluding a fixed portion, and in which said swingable means includes aleaf spring member, one end of said leaf spring member being operativelysecured to said fixed portion, and the freely swingable end of said leafspring member being operatively connected to said pressure sensitivemember.

7.. In a fluid mechanism having a fluid chamber with an aperturetherein, a fluid pressure sensitive member disposed within said apertureto comprise a movable portion of a wall of said chamber, means to mountsaid pressure sensitive member and to position same to provide apredetermined clearance space between its perimetrical surface and theadjacent surface forming said aperture, the fluid which acts on saidpressure sensitive member passing throughsaid clearance space whenever apressure difierential exists on opposite sides of said member, saidmounting means including a pair of spaced substantially parallel leafspring members imparting rigidity in one direction and acting tomaintain said perimetrical clearance in all operative positions of saidmember for substantially frictionless movements in a directiontransverse to said first named direction.

8. In a control mechanism for operating movable controlled means inaccordance with changes in a variable condition, means to effectmovement of said controlled means including a pressure sensitive memberresponsive to changes in said variable condition, a fluid chamber havingan aperture therein, said pressure sensitive member disposed within saidaperture to comprise a movable portion of a wall of said chamber, meansto mount said pressure sensitive member and to position same to providea predetermined clearance space between its perimetrical surface and theadjacent surface forming said aperture, the fluid which acts on saidpressure sensitive member passing through said clearance space whenevera pressure differential exists on opposite sides of said member, saidmounting means including substantially frictionless swingable meansimparting rigidity in one direction and acting to maintain saidperimetrical clearance in all operative positions of said member forsubstantial- '14 1V f ictionless movements in a direction transverse tosaid first named direction, the pressure in said chamber varying as afunction of said variable condition, whereby said pressure sensitivemember effects movement of said controlled means in response to changesin said variable condition.

9. The combination of elements defined in claim 2, and means to providerelative adjustment between said aperture and said pressure sensitivemember in a direction transverse to the direction of said substantiallyfrictionless movements of said member for making said clearancesubstantially uniform perimetrically of said member irrespective ofnormal production variations.

10. In a self regulating control mechanism for automatically controllinga variable condition, control means to regulate said controlledcondition, a servo motor operatively connected to actuate said controlmeans, a source of energy for said servo-motor, means to regulate theflow of said energy to said servo-motor to effect movements thereof andregulating movements of said control means, a pressure chamber havingfluid pressure therein varying as a function of said controlledcondition, a pressure sensitive member exposed to said fluid pressure insaid chamber and acting on said energy regulating means to effectmovements thereof in response to changes in said chamber pressure, saidchamber having an aperture therein, said pressure sensitive memberdisposed within said aperture to comprise a movable portion of a wall ofsaid chamber, means to mount said pressure sensitive member and toposition same to provide a predetermined clearance space between itsperimetrical surface and the adjacent surface forming said aperture, thefluid which acts on said pressure sensitive member passing through saidclearance space whenever a pressure diflerential exists on oppositesides of said member, said mounting means including substantiallyfrictionless swingable means imparting rigidity in one direction andacting to maintain said perimetrical clearance in all operativepositions of said member for substantially frictionless movements in adirection transverse to said first named direction.

11. The combination of elements defined in claim 10, in which saidpressure sensitive member includes an extension, and in which saidswingable means comprises a pair of spaced substantially parallel leafspring members, one end of each leaf spring member being operativelysecured to a support and the other end of each leaf spring member beingoperatively connected to said extension to effect said frictionlessmounting of said pressure sensitive member.

12. The combination of elements defined in claim 10, and means operatedby said control means for applying forces acting on said energyregulating means and varying in accordance with the movements of saidcontrol means.

13. In a governor mechanism in combination with an engine having meansto control the speed thereof, comprising a pressure responsive memberoperatively connected to said control means for actuation thereof, afluid circuit having a source of fluid pressure to cause a flow of fluidtherethrough and communicating with said pressure responsive member,valve means in said circuit for directing fluid therein to said pressureresponsive memher to effect movements thereof, a chamber having fluidpressure therein varying as a function of the speed of the engine, apressure sensitive member exposed to said fluid pressure in said chamberand acting on said valve means to eflect speed controlling movements ofsaid control means in response to changes in said chamber pressure, saidchamber having an aperture therein, said pressure sensitive memberdisposed within said aperture to comprise a movable portion of a wall ofsaid chamber, means to mount said pressure sensitive member and toposition same to provide a predetermined clearance space between itsperimetrical surface and the adjacent surface forming said aperture, thefluid which acts on said pressure sensitive member passing through saidclearance space whenever a pressure differential exists on oppositesides of said member, said mounting means including substantiallyfrictionless swingable means imparting rigidity in one direction andacting to maintain said perimetrical clearance in all operativepositions of said member for substantially frictionless movements in adirection transverse to said first named direction.

14. The combination of elements defined in claim 13, and said enginehaving an air passage in which said passage air pressure varies as afunction of the speed of said engine, and means providing fluidcommunication between said chamber and said passage air pressure totransmit same to said chamber for acting on said pressure sensitivemember to efiect said speed-controlling movements of said valve means.

15. In a fluid device to operate a movable member, the combination of apressure responsive member operatively connected to said movable memberto eflect movements thereof, a fluid circuit having a source of fluidpressure to produce a flow of fluid therethrough and communicating withboth sides of said pressure responsive member, valve means in saidcircuit to control pressures therein acting on said both sides of saidpressure responsive member, movements of said valve means increasing thepressure on one side of said pressure responsive member while decreasingthe pressure on the other side thereof, and conversely, to effectmovements of said pressure responsive member in response to movements ofsaid valve means, means associated with said valve means to apply forcesthereon for affecting the positioning thereof, a fluid chamber having anaperture therein, said last named force applying means including apressure sensitive member disposed Within said aperture to comprise amovable portion of a wall of said chamber, means to mount said pressuresensitive member and to position same to provide a predeterminedclearance space between its perimetrical surface and the adjacentsurface forming said aperture, the fluid which acts on said pressuresensitive member passing through said clearance space whenever apressure differential exists on opposite sides of said member, saidmounting means including substantially frictionless swingable meansimparting rigidity in one direction and acting to maintain saidperimetrical clearance in all operative positions of said member forsubstantially frictionless movements in a direction transverse to saidfirst named direction.

16. In a fluid device to operate a movable controlled member, thecombination of a pressure responsive member operatively connected tosaid controlled member to effect movements thereof, a fluid circuithaving a source of fluid pressure to produce a flow of fluidtherethrough and communicating with said pressure responsive member,valve means in said circuit to control pressures therein acting on saidpressure responsive member to effect movements thereof in response tomovements of said valve means, means associated with said valve means toapply forces thereon for affecting the positioning thereof, a fluidchamber having an aperture therein, said last named force applying meansincluding a pressure sensitive member disposed Within said aperture tocomprise a movable portion of a wall of said chamber, means to mountsaid pressure sensitive member and to position same to provide apredetermined clearance space between its perimetrical surface and theadjacent surface forming said aperture, the fluid which acts on saidpressure sensitive member passing through said clearance space whenevera pressure differential exists on opposite sides of said member, saidmounting means including substantially frictionless swingable meansimparting rigidity in one direction and acting to maintain saidperimetrical clearance in all operative positions of said member forsubstantially id frictionlessmovements in a direction transverse to saidfirst named direction.

17. The combination of elements defined in claim 16, in which saidsource fluid pressure acts on an area of said valve means to produceundesirable forces tending to disturb the desired position thereof, andsaid pressure sensitive member having an area subjected to said sourcefluid pressure to produce forces in a direction opposite to that of saidundesirable forces to compensate therefor in any desired amount.

18. In a fluid mechanism having a fluid chamber with an aperturetherein, valve means including a movable valve member for controlling aflow of fluid in said mechanism, a pressure sensitive member disposedWithin said aperture to comprise a movable portion of a wall of saidchamber, means to mount said pressure sensitive member and to positionsame to provide a predetermined clearance space between its perimetricalsurface and the adjacent surface forming said aperture, the fluid whichacts on said pressure sensitive member passing through said clearancespace whenever a pressure differential exists on opposite sides of saidmember, said mounting means including substantially frictionlessswingable means imparting rigidity in one direction and acting tomaintain said perimetrical clearance in all operative positions of saidmember for substantially frictionless movements in a directiontransverse to said first-named direction, said swingable means alsoacting to support said valve member for substantially frictionlessmovements in said direction transverse to said first-named direction bymaintaining said valve member suspended within the fluid controlledthereby completely free of surface contact other than fluid contactduring operational movements thereof.

19. In a fluid mechanism having a fluid chamber with an aperturetherein, valve means including a movable valve member for controlling aflow of fluid in said mechanism, a pressure sensitive member disposedWithin said aperture to comprise a movable portion of a wall of saidchamber, means to mount said pressure sensitive member and to positionsame to provide a predetermined clearance space between its perimetricalsurface and the adjacent surface forming said aperture, the fluid whichacts on said pressure sensitive member passing through said clearancespace whenever a pressure differential exists on opposite sides of saidmember, said mounting means including a pair of spaced substantiallyparallel leaf spring members imparting rigidity in one direction andacting to maintain said perimetrical clearance in all operativepositions of said member for substantially frictionless movements in adirection transverse to said firstnamed direction, said pair of leafspring members also acting to support said valve member forsubstantially frictionless movements in said direction transverse tosaid first-named direction by maintaining said valve member suspendedwithin the fluid controlled thereby completely free of surface contactother than fluid contact during operational movements thereof.

20. In a self-regulating control mechanism for automatically controllinga variable condition, the combination of control means to regulate saidcontrolled condition, a pressure responsive member operatively connectedto said control means for actuation thereof, a fluid circuit having asource of fluid pressure to produce a flow of fluid therethrough andcommunicating with said pressure responsive member, valve meansincluding a movable valve member in said circuit for controlling thefluid pressures therein acting on said pressure responsive member toeffect movements thereof and said control means, a chamber having anaperture therein and having fluid pressure therein varying as a functionof said controlled condition, a pressure sensitive member exposed tosaid fluid pressure in said chamber and acting on said valve means toeffect controlled-condition-regulating movements thereof in response tochanges in said chamber pressure, said pressure, sensitive memberdisposed within said aperture to comprise a movable portion of a wall ofsaid chamber, means to mount said pressure sensitive member to provide apredetermined clearance space between its perimetrical surface and theadjacent surface forming said aperture, the fluid'which acts on saidpressure sensitive member passing through said clearance space whenevera pressure differential exists on opposite sides of said member, saidmounting means including substantially frictionless swingable meansimparting rigidity in one directionand acting to maintain saidperimetrical clearance'in'all operative positions of said member forsubstantially frictionless movements in a direction transverse to said'first-named direction, said swingable means also acting to support saidvalve member for substantially frictionless movements in said idirection transverse to said 'fif'st-narned direction by maintainingsaid valve member suspended within the fluid controlled therebycompletely free of surface contact other than fluid contact duringoperational movements thereof, whereby the cooperative movements of saidpressure sensitive member and said valve member are substantiallyfrictionless and respond substantially instantaneously and consistentlyto minute changes in said chamber pressure to effect regulatingmovements of said control means.

21. The combination of elements defined in claim 20, and means operatedby said control means for applying forces acting on said valve memberand varying in accordance with the movements of said control means.

22. The combination of elements defined in claim 20, in which saidswingable means includes leaf spring means.

23. In a fluid device to operate a movable controlled member, thecombination of a pressure responsive member operatively connected tosaid controlled member to eifect movements thereof, a fluid circuithaving a source of fluid pressure to produce a flow of fluidtherethrough and communicating with said pressure responsive member,valve means including a movable valve member in said circuit to controlpressures therein acting on said pressure responsive member to effectmovements thereof in response to movements of said valve member, meansacting on said valve member to apply forces thereon for effecting thepositioning thereof, a fluid chamber having an aperture therein, saidlast-named force applying means including a pressure sensitive memberdisposed within said aperture to comprise a movable portion of a wall ofsaid chamber, means to mount said pressure sensitive member to provide apredetermined clearance space between its perimetrical surface and theadjacent surface forming said aperture, the fluid which acts on saidpressure sensitive member passing through said clearance space whenevera pressure differential exists on opposite sides of said member, saidmounting means including substantially frictionless swingable meansimparting rigidity in one direction and acting to maintain saidperimetrical clearance in all operative positions of said member forsubstantially frictionless movements in a direction transverse to saidfirst-named direction, said swingable means also acting to support saidvalve member for substantially frictionless movements in said directiontransverse to said first-named direction by maintaining said valvemember suspended within the fluid controlled thereby completely free ofsurface contact other than fluid contact during operational movementsthereof.

24. The combination of elements defined in claim 23, in which said valvemember controls pressure on only one side of said pressure responsivemember, and in which said fluid circuit includes two restrictionstherein, and said communication of said circuit with said pressureresponsive member on said one side thereof being at a point between saidtwo restrictions, and said movements of said supported Valve membervarying the restrictive effect of at least one of said restrictions toeffect movements of said pressure responsive member, and in which saidsource fluid pressure acts on an areaof said valve "member to produceundesirable forces tending to dissupport and the other end of each leafspring member being operatively connected to said unit to effect saidfrictionless support of said pressure sensitive member and said valvemember.

26. In a device to operate a movable controlled member and associatedwith an engine having an air passage, the combination of a pressureresponsive member operatively connected to said controlled member toeffect movements thereof, an air circuit communicating with said passageto induce a flow of air through said circuit and with said pressureresponsive member, valve means including a movable valve member in saidcircuit to control air pressures therein acting on said pressureresponsive member to effect movements thereof in response to movementsof said valve member, means to act on said valve member to apply forcesthereon for effecting the positioning thereof, a fluid chambercommunicating with said air circuit and having an aperture therein, saidlastnamed force applying means including a pressure sensitive memberdisposed within said aperture to comprise a movable portion of a wall ofsaid chamber, means to mount said pressure sensitive member to provide apredetermined clearance space between its perimetrical surface and theadjacent surface forming said aperture, the fluid which acts on saidpressure sensitive member passing through said clearance space whenevera pressure differential exists on opposite sides of said member, saidmounting means including substantially frictionless swingable meansimparting rigidity in one direction and acting to maintain saidperimetrical clearance in all operative positions of said member forsubstantially frictionless movements in a direction transverse to saidfirstnamed direction, said swingable means also acting to support saidvalve member for substantially frictionless movements in said directiontransverse to said first-named direction by maintaining said valvemember suspended within the fluid controlled thereby completely free ofsurface contact other than fluid contact during opera tional movementsthereof, the portion of said circuit between said chamber and said airpassage being substantially unrestricted for subjecting said pressuresensitive member to the pressures existing in said passage to eifectmovements of said pressure sensitive member and said valve member inresponse to changes in said passage pressure.

27. In a self-regulating control mechanism for automatically controllinga variable condition, the combination of control means to regulate saidcontrolled condition, a pressure responsive member operatively connectedto said control means to eflect movements thereof, a fluid circuithaving two parallel branch circuits and having a source of fluidpressure to cause a flow of fluid therethrough, said pressure responsivemember communicating on one side thereof with one of said branchcircuits and on the other side thereof with the other of said branchcircuits, valve means responsive to changes in said controlled conditionand including a movable valve member to control pressures in said twobranch circuits to vary oppositely and simultaneously the pressuresacting on opposite sides of said pressure responsive member to effectmovements thereof and said control means in response to movement of saidvalve means, a fluid chamber having an aperture therein, a pressuresensitive member effecting operation of said valve means and disposedWithin said aperture to comprise a movable portion of a wall of saidchamber, means to mount said pressure sensitive member to provide apredetermined clearance space between its perimetrical surface and theadjacent surface forming said aperture, the fluid which acts on saidpressure sensitive member passing through said clearance space Whenevera pressure difierential exists on opposite sides of said member, saidmounting means including a pair of spaced substantially parallel leafspring members imparting rigidity in one direction and acting tomaintain said perimetrical clearance in all operative positions of saidmember for substantially frictionless movements in a directiontransverse to said first-named direction, said pair of leaf springmembers also acting to sup- 2Q? port said valve member for substantiallyfrictionless movements in said direction transverse to said first-narneddirection by maintaining said valve member suspended Within the fluidcontrolled thereby completely free of surface contact other than fluidcontact during operational movements thereof.

References Cited in the file of this patent UNITED STATES PATENTS1,620,131 Price Mar. 8, 1927 2,156,496 Handwerk May 2, 1939 2,505,292Mallory Apr. 25, 1950 2,584,418 Branson Feb. 5, 1952 FOREIGN PATENTS443,335 Great Britain Feb. 26, 1936

